The procedure for creating a new MD region is very similar for all the different RAID levels. When using the EVMS GUI or Ncurses, first choose the menu item. A list of region-managers will open, and each RAID level will appear as a separate plug-in in this list. Select the plug-in representing the desired RAID level. The next panel will list the objects available for creating a new RAID region. Select the desired objects to build the new region. If the selected RAID level does not support any additional options, then there are no more steps, and the region will be created. If the selected RAID level has extra creation options, the next panel will list those options. After selecting the options, the region will be created.
When using the CLI, use the following command to create a new region:
create:region,<plugin>={<option_name>=<value>[,<option_name>=<value>]*},
<object_name>[,<object_name>]*
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For <plugin>, the available plug-in names are "MDLinearRegMgr," "MDRaid0RegMgr," "MDRaid1RegMgr," "MDRaid5RegMgr," and "MD Multipath." The available options are listed in the following sections. If no options are available or desired, simply leave the space blank between the curly braces.
The Linear-RAID and Multipath levels provide no extra options for creation. The remaining RAID levels provide the options listed below.
RAID-0 has the following option:
This option represents the granularity of the striped data. In other words, the amount of data that is written to one child object before moving to the next object. The range of valid values is 4 KB to 4096 KB, and must be a power of 2. If the option is not specified, the default chunk size of 32 KB will be used.
RAID-1 has the following option:
This option is the name of another object to use as a "hot-spare." This object cannot be one of the objects selected in the initial object-selection list. If no object is selected for this option, then the new region will simply not initially have a spare. More information about spare objects is in the following sections.
RAID-4/5 have the following options:
This is the same as the chunksize option for RAID-0.
This is the same as the sparedisk option for RAID-1.
Choose between RAID4 and RAID5. The default value for this option is RAID5.
If the RAID-5 level is chosen, this option allows choosing the desired parity algorithm. Valid choices are "Left Symmetric" (which is the default), "Right Symmetric," "Left Asymmetric, and "Right Asymmetric." If the RAID-4 level is chosen, this option is not available.